1. Field of the Invention
The present invention relates to an apparatus for surface treatment of metal parts by cataphoresis, and, more particularly, to surface treatment of motor vehicle bodies by cataphoresis.
2. Description of the Related Art
Treatment of surfaces by cataphoresis is accomplished by transporting the bodies through a treatment vessel along two parallel rails. The two parallel rails supply current to each of the bodies to be treated and are divided into portions, called dividing zones, separated by an insulating material, each rail portion supplying current from a different current source. However, the conventional treatment device results in coating defects because each body to be treated encounters several periods where current is cut off. During the passage of the bodies along the insulating material, the corresponding current source is cut off. With the conventional device, the current to each body is switched on and off, creating erratic current surges and causing coating defects.
Furthermore, the conventional device is disadvantageous because the actual dip time of the body part in the vessel becomes shorter due to the periods when the current is cut off. Thus, the treatment devices of the related art must be lengthened to obtain the dip time necessary for the treatment of the part. Otherwise, the rate of speed of the treatment process must be slowed. In either case, the conventional device produces defective coatings and is inefficient.